Harold Pinter was the greatest English playwright of the 20th century ... What amazed me, more and more, were his enraged political outbursts. However critical one might be of US policy, his furious anti-Americanism – “the most dangerous power that has ever existed” – was unworthy of an intelligent man. It is simply silly to compare American foreign policy with Nazi imperialism, as he did, and to insist that western governments are as evil as any of the worst in the world. To give his public support to the International Committee to Defend Slobodan Milosevic was unforgivable. Naturally, Pinter won the Nobel prize.

Wondering about Pinter’s dotty political positions, I began to understand an odd natural law of literature: creative writers are often silly political commentators. This is puzzling, because we tend to turn to creative writers for wisdom and understanding of the world. However, it is surprisingly often true that they have nothing sensible to say outside their fiction.

The most obvious example of this literary law is Tolstoy, one of the most understanding and observant of novelists. However, about politics he was simply silly. I am not talking about the astonishing gulf between his subtle writing about women’s feelings and his vicious treatment of his own wife; that disjunction is so common that it seems almost to be necessary to the creative mind. What I mean is the nonsense of his pamphlets and his public posturing.

Jean-Paul Sartre is another glaring example. His novels and plays may be out of fashion but there’s no doubt that he was a creative writer of talent. However, his politics were ludicrous. In his loathing of America, he supported the mass murderers Stalin and Mao, as – to my amazement – did the great poet Pablo Neruda, another Nobel laureate.

On the other silly side of the political spectrum, there is V S Naipaul, one of my favourite writers and a man of infinite subtlety in his creative work who, in public pronouncements on the state of the world, descends into nasty right-wing ranting that distresses all his admirers. The best and the worst of the 19th-century romantic poets also had daft political ideas. Graham Greene supported the Soviet Union, as did Bertolt Brecht. Martin Amis, one of the most gifted novelists since the war, found his political views parodied (very cleverly) by Bernard Levin for their childishness.

We probably shouldn’t count Ezra Pound, T S Eliot’s much-admired “better craftsman”, because he was probably mad, but as well as an inspired poet he was an active fascist in Mussolini’s Italy. Nor should we count Céline, the notorious French antisemite, who was probably mad as well. But there are plenty of sane writers, good and adequate, who confirm the rule. Of course there are writers to whom it doesn’t apply – such as Chekhov – but that may be because many of them simply chose to say little in public about politics. Perhaps there could be a New Year’s Eve party game – spot the writer without any silly political views.